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    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
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<body>
    
<script>
    var r = prompt('请输入圆的半径：');
    var h = prompt('请输入圆柱的高：');
    var PI =3.1415926;
    var sum=r*r*PI*h;
    alert('圆柱的面积为：'+sum.toFixed(3));
</script>
</body>
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